Vulcanizing System Dependence of the Rubbery Swelling, Dielectric and Doppler Shift Characteristics of IIR/EPDM Blends

Effect of the vulcanizing system on the rubbery swelling, dielectric and
Doppler shift characteristics of IIR/EPDM -carbon black (GPF) blends have
been studied. Three different vulcanizing systems were used in this study
namely, elemental sulphur (S-system), TMTD (T-system) and elemental sulphur
+ TMTD (M-system). The dielectric behaviour of the tested blends has been
studied in the frequency range from 1KHz to 100KHz and in the temperature
range from 40oC to 140oC. It has been observed that samples vulcanized with
(T-system) give a higher dielectric permittivity values compared with those
crosslinked with (S-system) or (M-system). The presence of the polar group < br />C=S in the TMTD molecules is the most effective factor on the dielectric
properties of the tested blends. The swelling behaviour and the positron
annihilation characteristics by means of Doppler Broadening parameters for the
tested blends have been investigated. The positron annihilation characteristics
supported the swelling and dielectric measurements obtained.